The invention relates to a fluid-volume measuring apparatus with a device for temperature-dependent volume conversion containing: a temperature sensor with a plunger attached to the fluid-volume measuring apparatus, a motion transmitting device acted upon by the temperature sensor, and a regulating transmission, controlled by the motion-transmitting device and forming part of a summing mechanism driven by the fluid-volume measuring apparatus.
In a liquid-volume measuring apparatus of this kind disclosed in Siemens Zeitschrift, 1961, pages 378 to 380, the motion transmitting device consists essentially of a lever, engaged at one end by the plunger of the temperature sensor; the other lever end interacts with the linkage of a regulating transmission configured in the form of a friction wheel drive. The lever is fulcrumed approximately in its center, its fulcrum being moveable as a function of the coefficient of thermal expansion of the liquid flowing through the liquid-volume measuring apparatus at a particular time. This construction of the motion transmitting device enables a volume measurement of liquid to be taken referred to a specified temperature, because the regulating transmission, with the cooperation of the temperature sensor and the motion-transmitting device, sees to it that the volume, measured in excess for example as when the liquid temperature exceeds the specified temperature, is reduced to the correct value referred to the specified temperature.
The same characteristics are present in another liquid flow meter with a summing mechanism shown in Deutsche Auslegeschrift 1,200,003 where the motion-transmitting device contains a lever system whose one lever, cooperating with another lever, can be varied as to its effective length as a function of the prevailing liquid temperature. Because of the use of several levers, this motion-transmitting device is relatively costly, but it has the advantage that the response to the change in liquid volume measured is relatively accurate, the change in volume being caused by a temperature of the liquid deviating from the specified temperature. A set screw to change the length of the other lever appropriately is provided to adjust the motion transmitting device to the mean coefficient of expansion of the particular liquid.
The known liquid-volume measuring apparatus do not take into account the circumstance that, in many liquids, the coefficient of thermal expansion as a function of the liquid temperature is not constant; this applies particularly to liquid gases whose expansion characteristic is not linear. For this reason, temperature sensors have already been used with a liquid corresponding to the liquid to be measured. But this method entails the disadvantage that an accurate temperature compensation is provided only for that liquid to be measured which is in the temperature sensor.
Accordingly, it is an object of the invention to provide a fluid-volume measuring apparatus which successfully makes possible, at relatively low cost, a temperature-dependent volume conversion. It is also an object of the invention to provide such a temperature-dependent volume conversion also when the expansion characteristic of the fluid to be measured is not linear.